There exists, in space, a high level of ionizing radiation caused by the trapping of protons and electrons by the earth's magnetic field. Electrons are present in high earth orbits while electrons and protons are trapped in low and medium earth orbits. The ionizing radiation causes an accumulation of charge in electronic circuits which eventually results in a malfunction or failure of the circuits.
Shielding is a commonly used method for protecting radiation sensitive components. Currently, shielding members for electronics are basically flat slabs of high-Z metal or high-Z/low-Z compounds attached to either the top or top and bottom of an electronics package. Other methods use shielding material that encapsulates the component, providing insulated feed throughs for electronic interconnection. The current methods add significant weight to the electronics. The encapsulation method, although more effective than the current slabs, is more expensive and requires custom design and packaging for the electronics. The added weight poses significant concerns for electronics to be used in space applications. Launch costs for a satellite are approximately $10,000 per pound.
Another method for protecting sensitive electronics is to design a radiation tolerant die that can withstand high levels of ionizing radiation. These design methodologies can involve redundancy of electronic circuits, doping of the semiconductor material, and spacing of electronic circuits. These methodologies are not normally used in commercially available electronics and require increased cost for redesign and production.
Therefore there exists a need to provide an effective radiation shield for sensitive electronic components that is optimized for low weight for space applications.
There also exists a need for an effective radiation shield, optimized for low weight that can be applied to existing electronic components with only minor modification of the packaging.